3-D viewing has always been a novelty in the film industry. In the early days of the film industry, 3-D viewing was accomplished by utilizing different color lenses in glasses which were handed out at the viewing of a motion picture. By creating the film with two cameras operating from different angles and an appropriate selection of colors, the two images could be superimposed over each other and then separated out by the viewer with the use of the glasses. However, reception by the public of 3-D viewing was less than satisfactory. In recent years, technology has allowed a more acceptable 3-D system to be created, that being the utilization of Liquid crystal lenses which can be alternately turned on and off, such that two separate, color correct pictures are presented to the viewer during each frame of the motion picture, one for the left eye and one for the right eye. The transmissive nature of the lenses is merely alternated between left and right during each frame. Of course, this requires the frame rate to be twice that of a normal motion picture.
The 3-D glasses utilizing shutter controlled Liquid crystal lenses typically have an infrared transmitter disposed in the theater, with each set of glasses worn by the viewers having a receiver disposed on the glasses. A sync pulse is transmitted to the glasses at the frame rate of the motion picture. This sync pulse is converted to a digital signal such that a rising and falling edge exists. Each rising edge initiates the beginning of a frame wherein each of the left and right lenses are controlled to turn on and off during the frame. However, circuitry internal to the glasses is used to set the "duty cycle" of the on/off control function for each of the lenses. This is typically a fifty percent duty cycle; that is, the left lens is on for fifty percent of the frame and the right lens is on for the other fifty percent of the frame. One disadvantage to having this fifty percent duty cycle is that it assumes that both the left and the right eye are equally balanced and, further, it assumes that each of the left and right eyes of the individual has an immediate response; however, this is not so. The eyes of an individual can, in fact, be unbalanced and if the picture to the left eye is turned off at the same time that the picture to the right eye is turned on, there can be some ghosting effect perceived by the viewer between the two frames.